RADIOSENSITIVITY OF TUMORS
Tumors, like their cell of origin, differ in their susceptibility to radiation injury. In general, a poorly differentiated tumor is more radiosensitive than a well differentiated one of the same type.
1- Radio-sensitive tumours:
Destructive dose of radiation_causes no significant damage in adjacent normal tissues.
- Malignant lymphoma – Seminoma of testis
- Lymphoepithelioma -Dysgerminoma of ovary
Ewings tumour of bone.
2- Radio-responsive tumors:
Destructive dose of radiation could do some damage to adjacent normal tissues.
- Squamous and basal cell carcinoma.
- Breast carcinoma.
Destructive dose of radiation is equally destructive_to adjacent normal tissues.
Malignant melanoma N.B.
1 – Metastatic tumors are more radiosensitive.
2- Poorly differentiated tumors are more radiosensitive than well-differentiated.
Recurrence of tumours after irradiation
Recurrent tumors after irradiation are usually radioresistant because the few resistant cells which survive transmit the property of resistance to their descendants.